Multicellular velocity-modulated tube



Feb. 5, 1952 R. BERTEROTTIERE 2,

-MULTICELLULAR VELOCITY-MODULATED TUBE Filed May .10, 1949 76/VE K2357? TfROTT/ElQf Patented Feb. 5, 1952 Ren Berterottiere, Paris, France, 'assignor to Compagnie Generale de Telegraphic Sans Fil,

' a corporation of France Application May 10, 1949, Serial No. 92,374

In France May 20, 1948 3 Claims.

The present invention relates to velocity-modulated tubes of the type of those described in J. Berniers co-pending United States application Ser. No. 664,156 filed on April 23, 1946, now Patent No. 2,539,985. Such tubes are essentially formed by the association in parallel of a plurality of cells, each of which comprises an electron beam adapted to pass across a system of cavity resonators of prismatic shape with a rectangular or trapezoidal base, or of sectorial cylindrical shape bounded by two concentric surfaces. Said resonators are provided over the whole or a part of their height with a re-entrant portion across which the-beam is adapted to pass, and the successive resonators are arranged either in a straight line or in a circle, the system providing in the latter case a radially symmetrical tube.

One of the chief difficulties of construction encountered in this type of tube is the impossibility of tuning the cells in an efiicient and simple manner by deforming their walls.

Certain devices proposed, such as inserting a piston into the inductive portion of the resonators, give only an extremely narrow tuning band.

The object of the invention is to enable simple tuning over a wide band to be obtained in tubes of this type. r v

The improvement according to the invention comprises eliminating one of the operative cells in the row or in the belt of such cells, and mounting the deformin means in the portion of the enclosure that corresponds to the eliminated cell.

'With said improvement are associated suitable embodiments of the deforming means.

The figure of the accompanying drawing shows by way of example a sectional plan view of a multi-cellular klystron to which the improvement according to the invention is applied.

The figure shows a sectional plan view of a radially symmetrical klystron comprising a plurality of cathodes ll, an inner belt of cavities l8, an outer .belt of cavities l9, and-Ea plurality of similar anodes 20 only one of which is illustrated. The cross-sectional shape of the resonators shown herein corresponds to the shape of Fig. 8 J. Berm'ers aforesaid co-pending application, but it is to be understood that the shape specified in my co-pending application, for Multi-cellular Velocity Modulated Tubes Serial No. 92,373, filed May 10, 1949, could just "as well be used without afiecting the possibility of applying the improvements hereinafter described. The resonators of each belt are coupled to one another by eliminating the common walls,

but they could be coupled to one another by other means, for example by means of loops.

In the improvement according to the invention, a portion 33 of the outer belt is eliminated and the corresponding cavity resonator 34 of the inner belt is replaced by a special cell in which the front surfaces of the re-entrant portion 35 are solid while the outer cylindrical wall 36 is replaced by a fiat'or slightly concave wall. By these means the inner belt can be readily reached in order to enable deforming means to be applied thereto which will act on a wall that has been rendered readily deformable.

In the same manner, a resonator of the outer .belt is replaced by a cell 31 with a solid re-entrant portion and a fiat or slightly concave outer wall, while the corresponding inner resonator 38 is rendered inoperative by interposing the walls 39. In this manner, the wall of the outer .belt is also rendered readily deformable.

Furthermore, the elimination of a cell in each of the belts has the advantage of introducing a gap between the input and the output of the chain of oscillating circuits formed by the cells and of thereby preventing reaction which may be objectionable in the case in which it is desired to use the tube as an amplifier.

The decrease in inductance produced by the shape given to the wall is compensated by the increase in capacitance" that corresponds to the front surfaces of the re-entrant portion which are no longer hollow tofiallow the beam to pass. but solid. The tuningzljfrequency of the special cell can therefore be lge'p't at the same value as that of the operative cells.

In the case in which} the magnitude of .the deformation which it is; desired .to obtain is not too great for examplein the case of an amplifier operating on a given frequency, it would however be possible to restore the hollow shape of the re-entrant portion, the beam and the anode, by providing a suitable deforming system round the anode. In this case, the capacitance of the cell cannot be increased by widening the front surfaces, since the overlap of the high-frequency field might become preclusive. On the other hand, it is possible in this case to increase the capacitance by mountin grids in the passage of the beam across the cavity resonator.

.In the figure, the suitable deforming means for the system in question are shown schematically.

said means comprising for example a core 40 which is secured to the stationary portion of the cavity resonator and is provided at its pe riphery with a toothed portion ll driven by a 1. A velocity -modulation tuhehaving a phi-j rality of cells each comprising a cathode, an

anode, a first cavity resonator and a second cayity resonator, the first cavity resonator of each adjustment cavity resonator having at least one deformable wall, the second'cavity resonator of I each cell communicating with the second cavity resonator of each of the other cells and with a second adjustment cavity resonator having at least one deformable wall, and mechanicalmeans connected to said adjustment cavity resonators for deforming the walls of said adjustm t ca y resonators. V,

2. A"-tube according to claim 1 wherein: the

cells and the adjustment cavity resonators are circular, the first cavity resonators and the second adjustment cavity resonator being arranged along an inner circle and the second cavity resonators and the second adjustment cavity resonator being: arranged along an omen-concentric ,circle. 1

3. A tube according to claim 1 wherein the adjustment cavity resonators have a re-entrant "1o cross-section with a solid re-entrant portion.

cell communicating with the*first-cavityreso 7 nator of each of the other cells and with a first BERTEROTTIERE.

M I .VREFERENCES CITED The following references are of record in the 15 file of this patent:'

UNITED STATES PATENTS Number Name Date 2,207,846 Wolfi July 16, 1940 2 2,320,860 Frernlin June 1, 1943 2,466,067 Woodyard et a1. Anr. 5, 1949 

